Optical coupler for optical imaging visualization device

ABSTRACT

An optical coupler for mounting at a distal end of an optical imaging device includes a visualization section and an attachment section. At least one surface of the visualization section has a roughness that does not interfere with a video capture system of an optical imaging device.

RELATED APPLICATIONS

This application is a Continuation Application of U.S. application Ser.No. 15/259,452 filed Sep. 8, 2016, now U.S. Pat. No. 9,709,795, which isa Continuation Application of U.S. application Ser. No. 14/494,090 filedSep. 23, 2014, now U.S. Pat. No. 9,459,442, the entire contents of whichare incorporated herein by reference.

BACKGROUND Field of the Invention

This disclosure relates to an optical coupler having one or moresurfaces with a defined degree of roughness for improved optical imagingof target areas by an optical imaging visualization device, such as anendoscope, laparoscope, arthroscope, ophthalmoscope, borescope, or otherremote imaging visualization technology.

Description of the Related Art

Remote optical visualization devices such as endoscopes and otheroptical imaging visualization devices illuminate surfaces and otherobjects a distance from the user of the visualization device, allowing auser to perform a diagnosis or procedure using images and signalsgenerated and transmitted a distance from the observed object. This caninclude, for example, viewing tissue inside a body cavity or a lumen,inspecting a hydraulic line in an aircraft, inspecting an oil pipelinefor leaks, or inspecting a sewer line for leaks and/or blockages. Remoteoptical visualization devices transmit these images to the viewer in avariety of ways, including, among others, through the use of (i) relaylenses between the objective lens at the distal end of the scope and aneyepiece, (ii) fiber optics, and (iii) charge coupled devices (CCD) andcomplementary metal oxide semiconductor (CMOS) sensors. Frequently, avideo capture system is connected to the optical visualization device todisplay a video image on a display monitor that can be viewed by a userduring use of the optical visualization device, including the ability toadjust the focus of the display through manual adjustments or autofocuscapability in a video processor system used with the optical imagingdevice. To achieve video capture with a video processor system, anobjective lens of an optical visualization device focuses lightreflected from a target being observed on an image sensor. The imagesensor outputs signals based on the detected reflected light. Thesignals from the image sensor are output to a signal processor, whichtypically includes imaging software that controls an autofocus featureconnected to the objective lens to adjust the in-focus object planeposition. A control signal generated by the signal processor activatesan autofocus operation to automatically bring the target being observedinto focus.

Optical couplers positioned over the objective image capturing elementof an optical visualization device allow improved remote observation inareas of the body where visibility has been obstructed by blood, stomachcontent, bowel content, or other opaque fluids and/or solid particulatematter. Optical couplers also allow improved remote observation innon-medical applications where visibility has been obstructed by fluidsand/or solid particulate matter. However, imperfections on the surfaceof the optical coupler may inhibit the visualization of the opticalvisualization device, including confusing the signal processor of anoptical visualization device using a video capture system, causing theautofocus feature to focus the objective lens on a surface of theoptical coupler, rather than on the intended target to be observed.Further, when an optical coupler is used with visualization systems thatdo not use image capture software, visualization may be hindered whenthe light from the visualization system passes through imperfections onthe distal surface of the optical coupler resulting in increased lightreflection and increased glare due to these imperfections. This mayoccur when light proceeds through the optical coupler and when lightreturns back through the optical coupler to the scope camera.

It would be advantageous to provide an optical couple that allowsimproved remote visualization while not interfering with the autofocusfeature of a video capture system and not causing increased lightreflectance and glare due to improved surface finish.

SUMMARY

Optical couplers in accordance with the present disclosure attach to thedistal end of a remote visualization device, such as an endoscope, andthe optical couplers have a surface with a defined degree of roughness.In embodiments, a surface of the optical coupler has a Root Mean Square(RMS) Roughness below about 20 nanometers, in embodiments from about 5nanometers to about 18 nanometers. In embodiments, the surface roughnessof the optical coupler surface is below about 0.5 nanometers, inembodiments from about 0.1 nanometers to about 0.4 nanometers. Inembodiments, a surface of the optical coupler has a Root Mean Square(RMS) Roughness below about 20 nanometers with spatial frequenciesbetween 1×10-1 mm-1 to 1×103 mm-1, in embodiments Y from about 5nanometers to about 18 nanometers for a similar spatial frequency range.

The “surface roughness of the optical coupler surface is below about 0.5nanometers” means that one of the center-line mean roughness (Ra), theten-point height irregularities (Rz), and the maximum height roughness(Rmax) is less than 0.5 nanometers, ±0.05 nanometers. In embodiments, asurface of the optical coupler has a center-line mean roughness (Ra) ofno more than about 0.5 nanometers, in embodiments, from about 0.1nanometers to about 0.4 nanometers. In embodiments, a surface of theoptical coupler has a ten-point height irregularities (Rz) of no morethan about 0.5 nanometers, in embodiments, from about 0.1 nanometers toabout 0.4 nanometers. In embodiments, a surface of the optical couplerhas a maximum height roughness (Rmax) of no more than about 0.5nanometers, in embodiments, from about 0.1 nanometers to about 0.4nanometers. In embodiments, a surface of the optical coupler has anaverage defect density of no more than about 100 defects per 10 μm², inembodiments from about 10 defects per 10 μm² to about 75 defects per 10μm². In embodiments, the distal surface of the optical coupler has adefined degree of roughness. In embodiments, the surface of the opticalcoupler closest to the objective lens of the endoscope has a defineddegree of roughness.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a side view of a first embodiment of an optical coupleraccording to the invention;

FIG. 2 is a cross-sectional view of the optical coupler of FIG. 1 takenalong line 2-2 of FIG. 1; and

FIG. 3 is a cross-sectional view of the optical coupler of FIGS. 1 and 2taken along line 3-3 of FIG. 2, the optical coupler being attached to anendoscope.

The figures depict specific embodiments of the present disclosure forpurposes of illustration only. One skilled in the art will readilyrecognize from the following discussion that alternative embodiments ofthe structures and methods illustrated herein may be employed withoutdeparting from the principles of the present disclosure describedherein.

DETAILED DESCRIPTION

The present optical couplers provide for improved optical imaging ofsurfaces covered with opaque fluids, semisolid materials or particulatematter, without interfering with the autofocus feature and other imagecapture and transmission elements of the optical imaging visualizationdevice and its related system elements. These advantages are provided byensuring that one or more surface(s) of the optical coupler in theoptical path has a defined degree of roughness, as described in moredetail below.

Turning now to FIGS. 1-3, an embodiment of an optical coupler 10 isshown. The optical coupler 10 includes a visualization section 12 at adistal end 13 of optical coupler 10. Visualization section 12 has agenerally slightly curved, convex outer surface 14 that extends from afirst outer side boundary 15 to a second opposite outer side boundary 16of optical coupler 10, and a proximal surface 18. In other embodiments,the visualization section may be non-curved and other embodiments may beconcave. Outer surface 14 may be spaced apart from proximal surface 18of optical coupler 10 by a length D (see FIG. 1). In some embodiments, ahollow instrument channel 19 extends from proximal surface 18 towardouter surface 14. Instrument channel 19 may not extend all the waythrough visualization section 12 to the outer surface 14. In such acase, a barrier section 20 of material is provided between a distal end21 of instrument channel 19 and outer surface 14 of optical coupler 10.

Optical coupler 10 also includes an attachment section 22 connected toand extending away from visualization section 12. Attachment section 22is at the proximal end 23 of optical coupler 10. In the embodimentshown, attachment section 22 is in the form of a cylindrical wall 24.Proximal surface 18 and cylindrical wall 24 of optical coupler 10 definea cylindrical opening 25 of optical coupler 10 within cylindrical wall24. In other embodiments, the optical coupler may be attached in othermanners, including using a gel or glue.

Referring to FIG. 3, optical coupler 10 can be mounted on an endoscope30. Endoscope 30 has a distal end 31 that is inserted in cylindricalopening 25 of optical coupler 10. Endoscope 30 has a sheath 32 with anouter surface 33 that snugly engages cylindrical wall 24 of opticalcoupler 10. An end surface 34 of endoscope 30 sealingly engages proximalsurface 18 of optical coupler 10. Endoscope 30 includes a first lumen35, a second lumen 36 and a third lumen 37 that extend from end surface34 of endoscope 30 to a proximal end (not shown) of endoscope 30. Alight guide 39 positioned in the first lumen 35 transmits light toward asurface area at or beyond outer surface 14 of optical coupler 10. Anobjective lens 40 is optically connected to a distal end of imagecarrying fiber 42. Objective lens 40 receives light reflected from thesurface area being viewed and image carrying fiber 42 transmits thereflected light to a video capture system (not shown) at a proximal end(not shown) of image carrying fiber 42. Objective lens 40 and imagecarrying fiber 42 are located in second lumen 36. Third lumen 37 alignswith hollow instrument channel 19 of optical coupler 10 when opticalcoupler 10 is mounted on endoscope 30. Optical coupler 10 can alsoinclude a Light Emitting Diode (LED) 11 near outer surface 14 of thecoupler to provide illumination prior to optical coupler 10 contactingany fluids, tissue, or structure. LED 11 may be provided power via awire (not shown) in endoscope 30 or from an external source. Additionaldetails regarding the construction and alternative embodiments ofsuitable optical couplers can be found in Published U.S. PatentApplication No. US2012/0209074A1, the entire content of which isincorporated herein by this reference.

Outer surface 14 and proximal surface 18 of optical coupler 10 liewithin the optical path of objective lens 40. In accordance with thepresent disclosure, at least one of outer surface 14 or proximal surface18 of optical coupler 10 is provided with a defined degree of roughness.The degree of roughness is the aggregate of any textural constituentelements present on the lens. The size of the textural constituentelement is not particularly limited provided the overall degree ofroughness does not interfere with the visualization of the imagetransmitted by the image capture system associated with the endoscopeonto which the optical coupler has been mounted.

In embodiments, the outer surface of the coupler transmits both thelight used for illumination and the returning light used for imagingsimultaneously. This common-path illumination and imaging lens allowsfor uniform illumination of an object near or at the focal region of theoptical imaging visualization device. However because of this, anysurface defects may cause light to be refracted or reflected back towardthe camera and cause glare or reduced contrast. Also, even a very smoothtransmitting surface will reflect a small percentage of light due toFresnel reflections; therefore, the figure and location of the lenssurface must be controlled such that light emitted from the illuminationsource will not reflect as such angles as to cause unwanted glare alongwith the surface finish with a defined degree of roughness.

In embodiments, the length and the width of any given texturalconstituent element can both be 10 μm or less. In embodiments, thelength of the textural constituent element (size of the texturalconstituent element in the longer direction) is 3 μm or less and thewidth (size of the textural constituent element in the shorterdirection) 500 nm or less. In other embodiments, the length and thewidth of the textural constituent element are preferably in the range of3 μm to 50 nm. In embodiments, the depth of the textural constituentelement may be 15 nm to 200 nm.

In embodiments where outer surface 14 or proximal surface 18 of opticalcoupler 10 includes depressions, the depressions have an averagediameter less than 100 nanometers, in embodiments, from about 15 toabout 50 nanometers. The depressions may have an average depth less thanabout 100 nanometers, in embodiments from about 4 nanometers to about50. The depressions may have a density or an average density, meaningthe number of depressions per 100 square micrometers of surface or theaverage number of depressions per 100 square micrometers of surface, ofless than about 100 depressions per 100 square micrometers of surface,in embodiments from about 15 to about 50 depressions per 100 squaremicrometers of surface.

In embodiments, a surface of the optical coupler has a Root Mean Square(RMS) Roughness below about 200 Angstroms; in embodiments, from about 50Angstroms to about 180 Angstroms. In embodiments, the surface roughnessof the optical coupler surface is below about 0.5 nanometers, inembodiments from about 0.1 nanometers to about 0.4 nanometers. The“surface roughness of the optical coupler surface is below about 0.5nanometers” means that one of the center-line mean roughness (R_(a)),the ten-point height irregularities (R_(z)), and the maximum heightroughness (R_(max)) is less than 0.5 nanometers, 0.05 nanometers. Inembodiments, a surface of the optical coupler has a center-line meanroughness (R_(a)) of no more than about 0.5 nanometers, in embodiments,from about 0.1 nanometers to about 0.4 nanometers. In embodiments, asurface of the optical coupler has a ten-point height irregularities(R_(z)) of no more than about 0.5 nanometers, in embodiments, from about0.1 nanometers to about 0.4 nanometers. In embodiments, a surface of theoptical coupler has a maximum height roughness (R_(max)) of no more thanabout 0.5 nanometers, in embodiments, from about 0.1 nanometers to about0.4 nanometers. In embodiments, a surface of the optical coupler has anaverage defect density of no more than about 100 defects per 10 μm², inembodiments from about 10 defects per 10 μm² to about 75 defects per 10μm². In embodiments, outer surface 14 of optical coupler 10 has adefined degree of roughness. In embodiments, proximal surface 18 ofoptical coupler 10 (i.e., the surface closest to the objective lens ofthe endoscope) has a defined degree of roughness.

The degree of roughness can be determined by using any technique withinthe purview of those skilled in the art, such as, for example, a lasersurface analyzer or a stylus surface profiler, but it can also bedetermined, simply by direct observation of the surface and crosssection under SEM.

A defined degree of roughness is provided on a surface of the opticalcoupler using techniques within the purview of those skilled in the art.The specific method chosen will depend on a number of factors includingthe material from which the optical coupler is made.

Optical coupler 10 can be formed from a variety of materials exhibitingtransparency or translucency and biocompatibility in medicalapplications. In embodiments, an optical coupler for non-medicalapplications can be formed from a variety of materials exhibitingtransparency or translucency.

In embodiments, a rigid material, e.g., a resin material such ascycloolefin polymer or polycarbonate, is used to form the opticalcoupler. When rigid materials are used, they are typically molded andthen one or more surface is polished to impart a defined degree ofroughness. Polishing techniques are within the purview of those skilledin the art and include, for example, chemical-mechanical polishing,mechanical polishing, CMP processes, reactive ion etching (e.g., with asubstantially chemically etching component), physical etching, and wetetching.

In embodiments, a flexible material is used to form the optical coupler.Flexible materials are typically difficult to polish. Accordingly, whereflexible materials are used, a defined degree of roughness is providedon the surface of a mold and imparted to the optical coupler when it ismolded.

In embodiments, the mold is prepared by any technique within the purviewof those skilled in the art, such as for example, the use of a series ofmicropolish compounds to prepare and refine the finish of the mold tothe point where the mold can produce an optical coupler with the desiredsurface finish on the optical coupler, and, alternatively, creating themold using single-point diamond turning to cut the surface of the moldwith a level of refined surface that the mold produces an opticalcoupler with the desired surface finish on the optical coupler.

In embodiments, optical coupler 10 is molded from a material selectedfrom glass, silicone gels, silicone elastomers, epoxies, polyurethanes,polycarbonates, acrylics, other elastic materials, and mixtures thereof.The silicone gels can be lightly cross-linked polysiloxane (e.g.,polydimethylsiloxane) fluids, where the cross-link is introduced througha multifunctional silane. The silicone elastomers can be cross-linkedfluids whose three-dimensional structure is much more intricate than agel as there is very little free fluid in the matrix. In otherembodiments, optical coupler 10 is made from a material selected fromhydrogels, such as polyvinyl alcohol, poly(hydroxyethyl methacrylate),polyethylene glycol, poly(methacrylic acid), and mixtures thereof. Thematerial for optical coupler 10 may also be selected from albumin basedgels, mineral oil based gels, polyisoprene, or polybutadiene. Inembodiments, the material is viscoelastic.

In embodiments, the optical coupler is a clear gel attached to the outerdistal portion of any optical imaging or image capturing device, such asan endoscope or camera lens. When pressed in contact with the surface ofan area to be viewed, the gel creates an offset that allows clearvisualization by mechanically displacing the opaque liquid or softsemisolids.

The material used to form the optical coupler can be comprised of two ormore compounds, for example an opaque compound attaches and holds twovisualization portions of a coupler in position, the first visualizationportion is an inner clear semi rigid compound shaped to match the fieldof view and minimum depth field of the imaging system, and the secondportion is attached to the outer boundary of the first visualizationportion and is composed of very soft gel providing additional area offluid displacement for maneuvering and positioning instruments underdirect vision. In embodiments, the two or more compounds each can be ofmaterials that exhibit transparency or translucency. Methods describedin U.S. Pat. Nos. 7,235,592 and 7,205,339 can be utilized to produce acoupler with portions or areas of the gel with different physicalproperties.

Referring back to FIGS. 1-3, in the optical coupler 10, the material isoptically clear such that the light guide 39 can transmit light throughthe optical coupler 10 toward a surface area at or beyond the outersurface 14 of the optical coupler 10 and such that the optical coupler10 is capable of transmitting an optical image of the surface area beingviewed back to the lens 40. In embodiments, the material has a degree oflight transmittance greater than 80% based on test standard ASTM D-1003(Standard Test Method for Haze and Luminous Transmittance of TransparentPlastics). In other embodiments, the material has a degree of lighttransmittance greater than 98% based on test standard ASTM D-1003. Inembodiments, the material has an optical absorption of less than 0.1% inthe visible light range, and, in embodiments, an optical absorption ofless than 0.01% in the visible light range. In embodiments, the materialhas an index of refraction of about 1.3 to about 2.2, and inembodiments, the index of refraction of the material matches the indexof refraction of the light guide 39, or is as low as possible.

The optical coupler 10 may also be coated. Coating may reduce the amountof adherence properties and/or reduce unwanted light reflections, and/orchange and enhance the optical coupler by adding hydrophobic orhydrophilic properties. Suitable coatings that may be used on theoptical coupler include, but are not limited to, polymers based onp-xylylene, such as for example, polymers that are commerciallyavailable under the trade name Parylene C, which is an optically clearbiocompatible polymer having abrasion resistant and hydrophobic orhydrophilic properties.

EXAMPLES

The following Examples have been presented in order to furtherillustrate the invention and are not intended to limit the invention inany way.

Example 1

A series of optical couplers in a shape similar to that of FIG. 3 wasmolded from Nusil MED-6033 an optical grade liquid silicone elastomeravailable from Nusil Technologies, Carpinteria, Calif. This silicone hasan index of refraction of 1.41, and a durometer of about 45 on the ShoreOO scale. The surface of the mold forming the outer surface of theoptical coupler was manufactured using a micropolishing methodology toimpart a surface finish better than the Society of Plastic Industry(SPI) A1 finish on to the mold. The surface finish of the mold and theresulting lenses were measured using a Zygo interferometer to determinethe surface finish on the distal surface of the optical coupler.

These optical couplers were then placed on a number of scopes, includingan Olympus CF-Q160A/L colonoscope, a 10 mm rigid laparoscope and aPentax EG-2990 gastroscope. The visual performance of these opticalcouplers was observed to determine the impact of surface finish on thevisual performance of these scopes without an optical coupler and withan optical coupler and the following was noted: The lenses measured withthis approach had the following attributes:

TABLE A Surface Surface Interfere Optical Roughness Roughness With ImageCoupler (RMS) (Ra) (Yes/No) 1 21.1646 nm 10.2766 nm Yes 2 40.3157 nm18.0538 nm Yes 3 32.9431 nm 13.8726 nm Yes 4 25.1743 nm 11.4089 nm Yes 512.0249 nm  8.5337 nm No 6 12.7432 nm 10.1406 nm NoTo further assess the variations in the surface finish of the opticalcouplers, assessments were performed by placing the couplers on thescopes mentioned above and moving various targets in close and away fromthe endoscope, at specific distances ranging from 3 mm out to severalcentimeters to assess how changes in light and object distance impactoptical performance, relative to surface finish. In addition, theoptical couplers were tested at these various distances in situationsinvolving fluid and debris to determine the impact of various levels ofsurface finish and various distances and environments on visualperformance. The performance of these optical couplers was compared tothe performance of a scope without the optical coupler to determine anacceptable surface finish that did not interfere with the capture of thevisual image through the optical coupler.

As can be seen from the data in Table A, a surface roughness of lessthan 12.7432 nm RMS did not interfere with the video capture andautofocus software, while surface roughness in excess of this level ofsurface roughness confused the software, and caused the image of targettissue displayed by the endoscope to be intermittently out of focus.Further, when lenses were tested on scopes without imaging software, theglare and reflection was unacceptably high, inhibiting performance, atthe surface roughness greater than 12.7432 nm RMS.

Persons skilled in the art will understand that the devices and methodsspecifically described herein and illustrated in the accompanyingdrawings are non-limiting exemplary embodiments. The featuresillustrated or described in connection with one exemplary embodiment maybe combined with the features of other embodiments. Such modificationsand variations are intended to be included within the scope of thepresent disclosure. As well, one skilled in the art will appreciatefurther features and advantages of the present disclosure based on theabove-described embodiments. According the present disclosure is not tobe limited by what has been particularly shown and described, except asindicated by the appended claims.

It should be understood that the foregoing description is onlyillustrative of the present disclosure. Various alternatives andmodifications can be devised by those skilled in the art withoutdeparting from the disclosure. For example, the coupler may be used innon-medical applications wherein the coupler is attached to the distalend of a borescope or attached to a micro, conventional, or roboticvideo cameras, inspection scopes, or still cameras, thereby allowingviewing and/or making repairs inside pipes, holding tanks, containers,etc. without the need to empty the pipes or containers of static ormoving opaque fluid, such as petroleum products, sewerage, foodproducts, paint, etc. In non-medical, industrial applications, thecoupler can be formed from materials that resist acid, alkalinity, highheat, or viscosity of fluid being displaced by the coupler and may bereusable. Accordingly, the present disclosure is intended to embrace allsuch alternatives, modifications and variances. The embodimentsdescribed with reference to the attached drawing figures are presentedonly to demonstrate certain examples of the disclosure. Other elements,steps, methods and techniques that are insubstantially different fromthose described above and/or in the appended claims are also intended tobe within the scope of the disclosure.

What is claimed is:
 1. An optical coupler for mounting at a distal endof an optical imaging device for visualizing a surface area, the couplercomprising: a visualization section at one end of the coupler, thevisualization section including a proximal surface and an outer surfacespaced apart from the proximal surface; and an attachment sectionconnected to and extending away from the visualization section, theattachment section being dimensioned to be mounted at the distal end ofan optical imaging device, at least one of the proximal surface or theouter surface of the visualization section having a roughness that doesnot interfere with an image capture system of an optical imaging device.